For starters
Stop electing dogmatics. Drop the social-conservative extremists. If you're going to kick realtively moderate like Lugar out, at least replace them with someone who isn't an idiot.
Science doesn't have to be a left-right issue, stop making it so.
If you want to run as a party that cuts taxes and reduces spending, then actually do it.
Don't sit there, cut taxes for some, increase spending for all then claim you're the only guys who can solve the deficit.
Don't run re-treads for President. Find someone fresher. Preferably not a stiff from Massachusetts with a fake tan.
(Not saying the Dems don't have their fair share of nuts too)